Free Reverse DNS Test

Enter an IP address to verify its PTR record and confirm FCrDNS setup. A missing or mismatched reverse DNS entry is one of the most common and easily fixed causes of email landing in spam.

Email Tester Inbox Placement Tester
IP Address: 
Welcome to Campaign Cleaners Forward Confirmed Reverse DNS Test Tool

1) Please fill out the IP Address you are testing.
2) Press Test.
Built with ♥ by Henry Timmes · Named contributor to RFC 7489 (DMARC)

What Is FCrDNS and Why Does It Affect Email Delivery?

When your mail server sends an email, the receiving server does a reverse DNS lookup on your sending IP. It expects to find a PTR record pointing to a hostname that matches your sending domain. FCrDNS (Forward-Confirmed Reverse DNS) takes this a step further: it then does a forward lookup on that hostname to confirm the IP matches. Both steps must pass for full verification.

This check is most relevant for organizations running their own mail servers on dedicated or cloud IPs. If you send through a major ESP, their infrastructure already handles PTR records. If you manage your own sending IP, this is one of the first things to verify when diagnosing deliverability issues.

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PTR Records

A PTR record maps your sending IP back to a hostname. It must be set by whoever controls the IP block, typically your hosting provider or ISP. You cannot set it through your domain registrar.

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The FCrDNS Check

FCrDNS performs two lookups: PTR on the IP to get a hostname, then an A record lookup on that hostname. If the A record resolves back to the original IP, the check passes. A mismatch at either step fails the test.

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Impact of Failure

A failed FCrDNS check causes receiving servers, especially Microsoft 365 and corporate gateways, to reject or spam-folder your email. It is one of the most actionable deliverability fixes because the cause and solution are both clear.

  1. Enter your sending server’s IP address in the field above and click Test.
  2. The tool will perform a PTR lookup and display the hostname your IP resolves to.
  3. It will then confirm whether that hostname’s A record resolves back to the same IP (the FCrDNS check).
  4. If the test fails, contact your hosting provider or ISP to request a PTR record pointing to your sending hostname.
  5. After updating, re-run this test to confirm the fix before sending.

Deliverability Tip: A good PTR record format is mail.yourdomain.com pointing back to your sending IP. Avoid generic hostnames like server123.datacenter.net as they signal a shared or unbranded IP to inbox providers, which can reduce trust even if the FCrDNS check technically passes.

Frequently Asked Questions

A PTR record maps an IP address back to a hostname. When you send email, receiving servers check the PTR record for your sending IP. If it is missing or does not match your sending domain, many servers will reject the message or route it to spam. PTR records are set by whoever controls the IP block, usually your hosting provider or ISP.

FCrDNS (Forward-Confirmed Reverse DNS) is a two-step validation. First, the PTR record for your sending IP is looked up to get a hostname. Then a forward DNS lookup (A record) is performed on that hostname. If the A record resolves back to the original IP, the check passes. This confirms the IP and hostname are genuinely associated, not just coincidentally matched.

PTR records must be set by the organization that owns the IP block, not through your domain registrar. If you send through AWS, Azure, or Google Cloud, they provide a way to set a custom PTR record in your instance settings. If you use a dedicated server from a hosting company, contact their support team and request a PTR record pointing to your sending hostname.

A failed FCrDNS check causes receiving servers to reject your email, defer it, or route it to the spam folder. Microsoft 365 and many corporate mail gateways are particularly strict about this check. It is one of the most actionable deliverability fixes available because it has a clear cause and a clear solution.

SPF lists which IP addresses are authorized to send email for your domain. FCrDNS confirms that the sending IP is legitimately associated with a hostname matching your domain. Both checks operate at the IP level and complement each other. Passing both significantly improves the trust score your email receives from inbox providers.

If you send through an ESP like Mailchimp, SendGrid, or Klaviyo, they manage PTR records for their shared sending IPs and FCrDNS is already configured on their infrastructure. This check is most relevant for organizations running their own mail servers on dedicated or cloud IPs where PTR setup is the sender’s own responsibility.

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